WASHINGTON -- Only half as many U.S. adolescents as in 2006 can still buy high-calorie sodas in school vending machines and stores, but they still have easy access to other sugary beverages, according to a study.

University of Michigan researchers surveyed more than 1,400 middle schools and more than 1,500 high schools to track beverages sold by schools outside of meal programs through vending machines, a la carte lines in the cafeteria, school stores and snack bars over four academic years beginning in 2006. The study, published in the Archives of Pediatrics & Adolescent Medicine on Aug. 6, was funded by the Robert Wood Johnson Foundation, a philanthropic organization aimed at improving U.S. health.

The researchers found that the percentage of high schoolers who could buy soda in school fell to 25% in 2011 from 54% in 2006, while access by middle school students fell to 13% from 27%. "Public school districts really have been getting the message that regular sodas are not a good thing for our kids to be drinking," said Yvonne Terry-McElrath, the study's lead author and a researcher at the university's Institute for Social Research.

The study found, however, that many students still have widespread access to other sugar-sweetened beverages, led by sports drinks, which were available to 55% of middle and 83% of high school students in the 2010-11 school year.

High-calorie drinks are the main source of dietary sugar among children, and offering these drinks at school can significantly increase students' daily calorie intake, the study said.

Although the number of middle school students with access to sports drinks declined significantly, 72% from four years ago, the same did not hold true for high school students. Eighty-three percent still had access to sports drinks in 2010-11, down from the 90% who did in 2006-07 -- which researchers say is still not enough.

While many schools still perceive sports drinks as healthy beverages, the researchers claim that they have a high sugar and salt content and that medical experts have said sports drinks should be limited to people doing intense exercise.

"Our study shows that, although schools are making progress, far too many students still are surrounded by a variety of unhealthy beverages at school," said Terry-McElrath. "We also know that the problem gets worse as students get older."

The study also showed that while students' access to higher-fat milk declined, in 2010 it remained available to 36% of middle school students and 48% of high school students.

Access to lower-fat milks stayed level among students at both school levels, and access to bottled water remained roughly the same for high school students. For middle school students, there was a slight decline in access to bottled water, likely due to the removal of vending machines from some schools, according to the study.

C. Tracy Orleans, senior scientist at the Robert Wood Johnson Foundation, said the progress being made to remove sugary sodas from schools is encouraging. "But while this study does have good news, it also shows that we're not yet where we want to be," Orleans said. "It's critically important for the USDA to set strong standards for competitive foods and beverages to help ensure that all students across all grades have healthy choices at school."

The study comes ahead of pending rules from the U.S. Department of Agriculture that will cover food and drinks sold in school vending machines, snack bars, school stores and cafeteria a la carte lines. | SEE STORY